Color negative films are a class of photosensitive materials that map the luminance (neutral) and chrominance (color) information of a scene to complementary tonal and hue polarities in the negative film. Light areas of the scene are recorded as dark areas on the color negative film, and dark areas of the scene are recorded as light areas on the color negative film. Colored areas of the scene are recorded as complementary colors in the color negative film: red is recorded as cyan, green is recorded as magenta, blue is recorded as yellow, etc. In order to render an accurate reproduction of a scene, a subsequent process is necessary to reverse the luminance and chrominance information back to those of the original scene. This subsequent process may or may not require another photosensitive material.
In the motion picture industry, there are two common subsequent processes. One such subsequent process is to optically print the color negative film onto another photosensitive material, such as Eastman Color Print Film 5386.TM., to produce a color positive image suitable for projection. Another subsequent process in the motion picture industry is to transfer the color negative film information or the color print film information into a video signal using a telecine transfer device. Various types of telecine transfer devices are described in Engineering Handbook, E. O. Fritts, Ed., 8th edition, National Association of Broadcasters, 1992, Chapter 5.8, pp. 933-946, the disclosure of which is incorporated by reference. The most popular of such devices generally employ either a flying spot scanner using photomultiplier tube detectors, or arrays of charged-coupled devices, also called CCD sensors. Telecine devices scan each negative or positive film frame transforming the transmittance at each pixel of an image into voltage. The signal processing then inverts the electrical signal in the case of a transfer made from a negative film in order to render a positive image. The signal is carefully amplified and modulated, and fed into a cathode ray tube monitor to display the image, or recorded onto magnetic tape for storage.
In the motion picture industry, the same color negative films are conventionally used for both subsequent processes, optical printing and telecine transfer to a video signal. In order to obtain a high quality visual image in an optical print, the mid-scale contrast (MSC) for each color record of the negative film is conventionally maintained equal to about 0.45 or higher, with higher levels being preferred for two or more records. Reduction of the contrast below this level in a negative would result in the production of flat-looking images in a positive print with black tones rendered as smokey-grey and white tones rendered as light gray. Pictures such as these would not be pleasing to view and would be deemed to be of low quality in the industry.
Images captured in a conventional color negative film designed for optical printing, however, can exhibit a loss of detail in highlights of high dynamic range scenes upon being processed with a telecine transfer device. Additionally, many telecine devices use light sources that are deficient in blue light output. Conventional negative films, which have relatively high blue minimum densities resulting from the presence of materials designed to improve the image quality of an optical print, can be difficult to scan on these telecine devices, and may exhibit excessive blue channel noise in a telecine transfer. These effects reduce the image quality obtainable in a telecine transfer, and can make the process of transferring film to video using a telecine device difficult and time-consuming. Loss in highlight detail in a telecine transfer is commonly caused by `burn-out` (high densities of a color negative film mapped to higher voltages than can be displayed on cathode ray monitors). Excessive `burn-out` makes film-to-video transfers difficult and time consuming.
While color print films have been designed specifically for use in making positives for telecine transferring, use of such print films adds additional processing steps and costs to forming a telecine transfer, and image information from the color negative can be lost in the print step. Accordingly, it would be desirable to make improved telecine transfers possible directly from a color negative film.